Rotational positioning mechanism for single element printer

ABSTRACT

A plurality of type characters are formed on the periphery of a typehead of a single element printer, and the typehead is rotatably driven to position selected type characters for printing by a belt drive extending into a cavity in the typehead. The typehead is removably secured to a gear rotatably supported on a tilt frame, and the tilt frame is pivotally mounted on a shaft which is rotatably supported in a portion of a supporting frame received in the cavity of the typehead. The shaft carries a beveled gear engaged with the gear associated with the typehead, and the typehead is rotatably driven by an endless toothed belt leading into the cavity of the typehead and trained about a toothed pulley carried on the shaft. The supporting frame is rotatably mounted on a bushing which is slidably carried on a drive shaft, and the toothed belt is trained about a toothed pulley on the bushing so as to enable the typehead to be rotatably driven upon rotational movement of the drive shaft.

[ Feb. 18, 1975 [57] ABSTRACT A plurality of type characters are formed on the periphery of a typehead of a single element printer, and the typehead is rotatably driven to position selected type characters for printing by a belt drive extending into a cavity in the typehead. The typehead is removably secured to a gear rotatably supported on a tilt frame, and the tilt frame is pivotally mounted on a shaft which is rotatably supported in a portion of a supporting frame received in the cavity of the typehead. The shaft carries a beveled gear engaged with the gear associated with the typehead, and the typehead is rotatably driven by an endless toothed belt leading into the cavity of the typehead and trained about a toothed pulley carried on the shaft. The supporting frame is rotatably mounted on a bushing which is slidably carried on a drive shaft, and the ROTATIONAL POSITIONING MECHANISM FOR SINGLE ELEMENT PRINTER Inventor: Herbert Decker, Lauf, Germany Assignee: Triumph Werke Nurnberg A.G.,

N urnberg, Germany Filed: Oct. 18, 1973 Appl. No; 407,551

Foreign Application Priority Data Oct. 26, 1972 Germany............................ 2252447 U.S. 197/55, 197/52 Int. B41j 1/32 Field of Search 197/16, 18, 52

References Cited UNITED STATES PATENTS United States Patent Decker toothed belt is trained about a toothed pulley on the bushing so as to enable the typehead to be rotatably driven upon rotational movement of the drive shaft.

4 Claims, 2 Drawing Figures ROTATIONAL POSITIONING MECHANISM FOR SINGLE ELEMENT PRINTER This invention relates to a single element printer, and more particularly to a mechanism for positioning a single print element for printing selected type characters.

In a typical single element printer, a plurality of type characters are disposed on the periphery of a generally spherical-shaped type carrier, hereinafter referred to as a typehead, which is supported for movement from a rest position to a print position. Selected type characters are positioned for printing by rotating and tilting the typehead, and printing is effected by moving the typehead to the print position where the selected type character is impacted against a recording medium.

Typically, the movement of the typehead to position a character for printing has involved a complicated drive arrangement. In an attempt to minimize the number of parts necessary to position a selected type character for printing, a spherical typehead has been rotatably driven by an external belt, chain or the like as shown in German Pat. No. 1,561,218 and corresponding US. Pat. No. 3,420,350. However, such an arrangement is disadvantageous since the belt is in an area of the typewriter which is accessible to a typist thereby creating a possibility of injury. Moreover, such an arrangement is limited to a spherical typehead, and the tilting movement of the typehead is likely to twist the belt causing excessive wear. Furthermore, the typehead is not easily exchangeable since the replacement of a particular typehead also involves the removal of the drive belt.

Accordingly, an object of the present invention is to provide a single element printer with a belt driven positioning mechanism wherein the belt is arranged so as to be less accessible to a typist, thereby reducing the possibility of injury to a typist.

Another object of the invention is to provide a single element printer with a belt driven positioning mechanism wherein the typehead is easily replaceable without removing the belt drive.

A further object of the invention is to provide a single element printer with a belt driven positioning mechanism wherein the typehead is movable to position a different type character for printing without twisting of the belt drive.

An additional object is to provide a single element printer with a belt driven positioning mechanism which is usable with typeheads having different configurations.

Still other objects, features and advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a partial diagrammatic view of a single element printer having a belt driven positioning mechanism constructed in accordance with the present invention; and

FIG. 2 is a partial sectional view of the single element printer taken along the lines 2-2 in FIG. 1.

Referring now in detail to the Figures in the drawing, there is shown a single element printer, generally indicated 11, for printing type characters on a recording medium, not shown, which may be suitably located on a cylindrical platen 13. The type characters, generally indicated 15, are formed on the periphery of a spherical or barrel-shaped typehead 17 which is carried by a support means, generally indicated 19, for movement from a normal rest position to a printing position at the platen 13. As is conventional, printing is effected by impacting a selected type character 15 against the platen 13, and the typehead 17 may be driven in a printing movement by a suitable drive means, for example a stepping motor, gear or crank drive, not shown, acting on the support means 19 through a drive arrangement, generally indicated 21. To enable a line of type to be printed, the support means 19 may be associated with a carriage, not shown, for movement past the platen 13, or alternatively the platen 13 may be mounted on a carriage for movement past the typehead 17. The recording medium and the means for moving the typehead 17 past the platen 13 as well as other portions of the printer are not shown since they form no part of the present invention and may be desirably conventional.

As shown, the typehead 17 is generally in the form of an inverted cup supported to rotation about a central top portion 23 and having an internal cavity 25 opening towards the support means 19. The support means 19 includes an elongated frame 27 with one end received in the cavity 25 of the typehead l7 and the other end terminated in a pair of spaced-apart arms 29, 29 rotatably supported on a bushing 31 which is slidably carried on a shaft 33. Although not shown, the support means 19 is associated with a carriage for movement past the platen l3 and is normally urged to a rest position by a spring 35 stretched between a suitable portion of the carriage and an arm 37 extending laterally from the elongated frame 27. The drive arrangement 21 includes a sheave 39 rotatably carried on the laterally projecting arm 37 and a pair of sheaves 41, 41 rotatably supported on the carriage at a forward location, and the typehead 17 is moved forwardly to the printing position by pulling on the end of a suitable rope or cable 43 which is trained around the sheaves 41, 39 and 41 with the other end suitably secured to the carrrage.

As is conventional, the type characters 15 are disposed on the periphery of the typehead 18 in circumferential rows and columns, and selected type characters 15 are printed by rotating and tilting the typehead 17 to position desired type characters 15 for impacting against the recording medium upon a printing movement of the support means 19 as described above. To enable the typehead 17 to be tilted for positioning type characters 15 in the different circumferential rows for printing, the typehead 17 is supported in a manner explained below on a tilt frame 45 which forms a portion of the support means 19 and is pivotally connected to the end of the elongated frame 27 received in the cavity 25 of the typehead 17. As shown, the tilt frame 45 has an arm 45 which is connected by a link 47 to a crank arm 49 which is slidably supported on a tilt shaft 51 for movement with the carriage. The crank arm 49 is rotatably connected to the tilt shaft 51 by means of a key 53 received in a slot 55 formed in the tilt shaft 51, and the tilt shaft 51 may be driven by a suitable stepping motor, gear or crank drive, not shown, so as to impart a tilting movement to the typehead 17.

In accordance with the present invention, the rotational movement of the typehead to position a selected type character 15 for printing is effected by drive means including a toothed belt 57 extending into the 3 4 cavity 25 of the typehead 17. As shown, the toothed 1. In a printing machine having a hollow downwardly belt 57 is trained about a toothed pulley 59 carried on open cup-shaped typehead on which a plurality of type the bushing 31 between the arms 29, 29 of the eloncharacters are located in columns and rows on its outer gated frame 27 and about another toothed pulley 61 periphery, said typehead being adapted to be rotatably carried on a shaft 63 which is rotatably supported at the positioned about a rotate axis to select a column of type other end of the elongated frame 27 which has a slot 65 characters and to be tiltably positioned about a tilt axis for receiving the toothed pulley 61. The shaft 63 also to select a row of type characters, comprising,

serves as the pivotal support for the tilt frame 45 and support means extending into the hollow interior of carries a beveled gear 67 driving another gear 69 assosaid typehead for supporting said typehead for ciated with the typehead 17. As shown, the gear 69 is movement about an external axis to effect printing rotatably mounted on the tilt frame 45 with a cylindriof a type character at a selected row and column cal projection 71 received thereof in a cylindrical bore location, 73 formed in an upwardly projecting hub portion 69 a first shaft defining said external axis, of the gear 69, and with a shoulder of a screw 75 rea second shaft parallel to said first shaft rotatably ceived through an axial bore 77 in the gear 69 and supported on the portion of said support means threaded into the cylindrical projection 71 of the tilt within said typehead, said second shaft defining frame 45. To enable the typehead 17 to be removably said tilt axis, secured to the gear 69, an opening 78 is formed in the a tilt frame pivotally supported on said second shaft, central top portion 23 for receiving the upwardly proa first gear rotatably supported on said tilt frame and jecting hub portion 69, and the typehead 17 may be having its axis along said rotate axis, locked to the gear 69 by a spring clip 79 received in an means securing said typehead to said first gear, annular groove 81 in the projecting hub portion 69 ada second gear secured to said second shaft meshing jacent the central top portion of the typehead 17. with said first gear,

In operation, the typehead 17 may be rotated to posia first pulley rotatably mounted on said first shaft, tion a selected type character 15 for printing by rotat- 2 5 a second pulley secured on said second shaft, ably driving the shaft 33 which is rotatably secured to drive means comprising a belt trained around said the bushing 31 by a key 31' slidable in a groove 33 first and second pulleys to rotatably position said formed in the shaft 33, and the shaft 33 may be rotattypehead about its rotate axis, ably driven by a suitable stepping motor, crank or gear and means for rocking said tilt frame about said secdrive. As the bushing 31 is rotatably driven, the toothed 0nd shaft to select a row of type characters without belt drive 57, 59, 61 rotates the shaft 63 to drive the twisting movement of said belt. beveled gear 67 which in turn rotatably drives the gear 2. In a printing machine as recited in claim 1 said 69 associated with the typehead 17. In addition, a tilttypehead having an upwardly extending central sleeve, ing movement of the typehead 17 to position different said first gear having a hollow shaft extending through circumferential rows of type characters 15 for printing said sleeve, and said tilt frame having a cylindrical promay be effected by rotating the shaft 55 to pivot the tilt jection extending into said hollow gear shaft.

frame 45. As described above, the tilt frame 45 is pivot- 3. In a printing machine as recited in claim 1, wherein ally supported about the shaft 63 and the tilting move said rotate and tilt axis intersect. ment ofthe typehead 17 may be accomplished without 4. In a printing machine as recited in claim 1, said twisting the toothed belt 57. typehead being barrel-shaped.

What is claimed is: 

1. In a printing machine having a hollow downwardly open cupshaped typehead on which a plurality of type characters are located in columns and rows on its outer periphery, said typehead being adapted to be rotatably positioned about a rotate axis to select a column of type characters and to be tiltably positioned about a tilt axis to select a row of type characters, comprising, support means extending into the hollow interior of said typehead for supporting said typehead for movement about an external axis to effect printing of a type character at a selected row and column location, a first shaft defining said external axis, a second shaft parallel to said first shaft rotatably supported on the portion of said support means within said typehead, said second shaft defining said tilt axis, a tilt frame pivotally supported on said second shaft, a first gear rotatably supported on said tilt frame and having its axis along said rotate axis, means securing said typehead to said first gear, a second gear secured to said second shaft meshing with said first gear, a first pulley rotatably mounted on said first shaft, a second pulley secured on said second shaft, drive means comprising a belt trained around said first and second pulleys to rotatably position said typehead about its rotate axis, and means for rocking said tilt frame about said second shaft to select a row of type characters without twisting movement of said belt.
 2. In a printing machine as recited in claim 1 said typehead having an upwardly extending central sleeve, said first gear having a hollow shaft extending through said sleeve, and said tilt frame having a cylindrical projection extending into said hollow gear shaft.
 3. In a printing machine as recited in claim 1, wherein said rotate and tilt axis intersect.
 4. In a printing machine as recited in claim 1, said typehead being barrel-shaped. 